WERTHEIMER: Some Internet users may be out of luck when they try to log on this morning. They're victims of an international malware attack - a malicious software picked up by their computers online over a year ago.

At one minute past midnight Eastern Time, the FBI turned off Internet servers set up as a stop-gap to keep tens of thousands of these victims online.

Last year, the FBI shut down a group of servers that were being used by hackers to control almost 600,000 computers around the world. The trouble was if the servers went offline, so would the infected computers. So the FBI contracted a private company to create two new, clean servers in the interim, and a website to help the victims get their computers disinfected.

Eight months later, the court order keeping those servers running has expired. They've been switched off. Any victims still infected by the malware will have to get their cyber-hygiene in order before they can get back online. Transcript provided by NPR, Copyright NPR.